package com.bristua.barcode.common.util;

import java.util.UUID;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class SequenceUtil {
    private static final long ONE_STEP = 10;
    private static final Lock LOCK = new ReentrantLock();
    private static final Lock LOCK2 = new ReentrantLock();
    private static long lastTime = System.currentTimeMillis();
    private static short lastCount = 0;
    private static int count = 0;
    @SuppressWarnings("finally")
    public static String nextId() 
    {
        LOCK.lock();
        try {
            if (lastCount == ONE_STEP) {
                boolean done = false;
                while (!done) {
                    long now = System.currentTimeMillis();
                    if (now == lastTime) {
                        try {
                            Thread.currentThread();
                            Thread.sleep(1);
                        } catch (InterruptedException e) {
                        }
                        continue;
                    } else {
                        lastTime = now;
                        lastCount = 0;
                        done = true;
                    }
                }
            }
            count = lastCount++;
        }
        finally 
        {
            LOCK.unlock();
            return lastTime+""+String.format("%03d",count); 
        }
    }
    public static String[] chars = new String[] { "a", "b", "c", "d", "e", "f",
            "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s",
            "t", "u", "v", "w", "x", "y", "z", "0", "1", "2", "3", "4", "5",
            "6", "7", "8", "9", "A", "B", "C", "D", "E", "F", "G", "H", "I",
            "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V",
            "W", "X", "Y", "Z" };


    public static String generateShortUuid() {
        StringBuffer shortBuffer = new StringBuffer();
        String uuid = UUID.randomUUID().toString().replace("-", "");
        for (int i = 0; i < 7; i++) {
            String str = uuid.substring(i * 4, i * 4 + 4);
            int x = Integer.parseInt(str, 16);
            shortBuffer.append(chars[x % 0x3E]);
        }
        return shortBuffer.toString();

    }

    public static void main(String[] args) {
        String s = SequenceUtil.generateShortUuid();
        System.out.println(s);
    }
}